This is a study of the interacting effects of iodide deficiency and supplementation and of protein deficiency and supplementation on intellectual, neurological, motor and physical development in a region of Andean South America where endemic goiter has been highly prevalent. Iodized oil has been administered in a controlled plan to the population group. The effects of this on goiter and on growth and development of children are measured. In the study on Ecuador surveillance begins as soon as pregnancy is ascertained. Lysine-tryptophane supplements to the maize diet are given in order to measure the effects on development of the progeny, and the results compared to controls. The code for the lysine-tryptophane supplements versus control supplements of glycine has not yet been disclosed. Emphasis in the Andean Peru study is on the effects of iodine prophylaxis on fetal-maternal relationships.